New exhaust install

[albuKat]

Installed the D&D full exhaust today, but am getting some crackling and popping on deceleration. This means I am lean, correct? I turned the fuel screws out 1/2 turn from stock. Do I need to turn them out more? I haven't jetted the carbs yet, and may not. I am just looking for anyone who has ran D&D with stock jets that might be able to help with adjustment.

Thanks

[arsenic]

yes, don't go 1/2 turn from what they are. Seat them and turn them to 2.5 turns out.

[albuKat]

when I first checked them, they were at 2.75 turns out. I went 1/2 out from there. If I go 2.5, won't it be leaner than what it was originally?

[arsenic]

it wasn't at 2.75 turns out with stock jetting. If it really is all stock NO WAY was it at 2.75 turns out.

[albuKat]

That's what I counted. I made a mark, turned past that mark 1/4 shy of 3 turns to seat it. I checked them all before I changed them.

oh, and I pulled the plugs out myself, so I know that nobody had messed with it before then.

[albuKat]

bump

So should I turn them out more??

[Liltroy]

Mine does the same thing with the yoshimura full system. I've been running it without any changes for a few weeks now. I'm planning on an Ivans jet kit but until then I guess I'll try fattening the mixture up as well. So, your screws were at 2.75 turns from the factory? What are they SUPPOSSED to be at stock?

[albuKat]

Mine is a 750, May be different from yours since it is a 600. Not sure what the stock setting is on it. Like I said, when I first checked them they WERE at 2.75 out, contrary to what Arsenic said. Right now, they are at 3.25 out and it is still popping. maybe a jet kit is the only real cure? I'm just worried because of all I read about the dangers of running too lean.

[slamcool]

Installed the D&D full exhaust today, but am getting some crackling and popping on deceleration. This means I am lean, correct? I turned the fuel screws out 1/2 turn from stock. Do I need to turn them out more? I haven't jetted the carbs yet, and may not. I am just looking for anyone who has ran D&D with stock jets that might be able to help with adjustment.

Thanks

Well.... most engines do a bit of that, when you decelerate, the engine may run a little rich (lack of oxygen) for a moment and a bit of unburned fuel may ignite in the exhaust manifold. That's what's causing the little popping. It's called afterfire and it cannot totally be avoided. One of the functions of a catalytic converter, is actually to get rid of that unburned fuel. All engines suffer from that problem, only you hear it a little more with a racing exhaust kit.

Don't play with your settings just for that. Unless it's more than a little popping like it seems to be the way you said it. If it does it in other times than just deceleration then yeah, could be your settings, running too lean or too rich may cause backfires or afterfires.

[albuKat]

Thanks Slamcool for the detailed description of what's going on. I always had a hard time understanding a lean condition causing an afterfire. The unused fuel from running too rich and causing them makes more sense to me.

So basically, leave it as is... and dont fix it if it isn't broken

[slamcool]

well said